From patchwork Fri Oct 9 16:13:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11826491 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1EB881580 for ; Fri, 9 Oct 2020 16:14:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07A902231B for ; Fri, 9 Oct 2020 16:14:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="rDHTl2DO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389789AbgJIQO1 (ORCPT ); Fri, 9 Oct 2020 12:14:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389747AbgJIQOS (ORCPT ); Fri, 9 Oct 2020 12:14:18 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B91ACC0613E6 for ; Fri, 9 Oct 2020 09:14:13 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id v4so5162834ybp.3 for ; Fri, 09 Oct 2020 09:14:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=ljsItlz/aE0P1FDke8OIPGTsfsgvR6SCQ5aAaAr+FuY=; b=rDHTl2DOvEF5lAI8/1xgnH7ewQP7v+fy6WFg1GImMEetNzxgNOGQtQTgFVZA7nJz4m E/V9TlOXQo2zsXvADw6ZjNHpbyo0GyLXq/UcXFopFQ5iYAVttrLb5kwsOMZlNj6d3mq2 v2Z69HCANswfC9sVB06+DLebakWFduI4MBn43M/w9uUpWzAIbBGEejEK5mHvIYhz912n egyvp5xLTL8ReK004BgDAz4wuj45irBJ5zvwJmj0uVsXV1gk7BqZvJNpws7d45/nZF1s sv/UzaMr8Prok4UlE5mODVRqtzkXlZAlSECInu3Rk5zSafDWjBxTBOhp32r/igI3DisM FvIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=ljsItlz/aE0P1FDke8OIPGTsfsgvR6SCQ5aAaAr+FuY=; b=sIW2iRO3qklxjXjk0eL9vbyb/5M6QVELYtedd9mw9z4yOKmXPoM/qpc2XKEMOKgw10 h+5WPQ4IZjbGikDGpC538Tm7fuj6ZJERzkt7G4L302s7YyVEYlswlkchd/KRDJcxTziG issdTsJ248iOmVH1ygQnUj377p74fuX5s/gb1dcvkpCOWPBTY3D3oNW0zo0gKw1S74A2 Zir4zJZUdXruBh/mLjrVU0ZeT/lQHaFmYAWbfjFDa1/y4B2eGpPBfcCNUgc57SvVJ13d p288sIWT4bgEccSerYlPalxjJIOPzM2jw/Q/1+OrFL5Q1R3PhBkX+rV9YOEvuU3wY9Wu WCmA== X-Gm-Message-State: AOAM533i+09Cv55lnbVS/FxJ7FA1ZkVFiiJhIh8nZESQkP2Ason1xBeU Z6+vQkAAeBtss+wYnq7GEuQhGIO+A4igg8+Dk0M= X-Google-Smtp-Source: ABdhPJy32BlRlXtKX3ZecjjCx8sYUdqfwZnP6p3172X1KprlyJNmmCaj7qPqSsBQi7a3XNa21VFXuJCMRei9tPIgOic= Sender: "samitolvanen via sendgmr" X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:f693:9fff:fef4:1b6d]) (user=samitolvanen job=sendgmr) by 2002:a25:aaae:: with SMTP id t43mr18851419ybi.404.1602260052989; Fri, 09 Oct 2020 09:14:12 -0700 (PDT) Date: Fri, 9 Oct 2020 09:13:25 -0700 In-Reply-To: <20201009161338.657380-1-samitolvanen@google.com> Message-Id: <20201009161338.657380-17-samitolvanen@google.com> Mime-Version: 1.0 References: <20201009161338.657380-1-samitolvanen@google.com> X-Mailer: git-send-email 2.28.0.1011.ga647a8990f-goog Subject: [PATCH v5 16/29] init: lto: fix PREL32 relocations From: Sami Tolvanen To: Masahiro Yamada , Will Deacon , Steven Rostedt Cc: Peter Zijlstra , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org With LTO, the compiler can rename static functions to avoid global naming collisions. As initcall functions are typically static, renaming can break references to them in inline assembly. This change adds a global stub with a stable name for each initcall to fix the issue when PREL32 relocations are used. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook --- include/linux/init.h | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) diff --git a/include/linux/init.h b/include/linux/init.h index af638cd6dd52..cea63f7e7705 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -209,26 +209,49 @@ extern bool initcall_debug; */ #define __initcall_section(__sec, __iid) \ #__sec ".init.." #__iid + +/* + * With LTO, the compiler can rename static functions to avoid + * global naming collisions. We use a global stub function for + * initcalls to create a stable symbol name whose address can be + * taken in inline assembly when PREL32 relocations are used. + */ +#define __initcall_stub(fn, __iid, id) \ + __initcall_name(initstub, __iid, id) + +#define __define_initcall_stub(__stub, fn) \ + int __init __stub(void); \ + int __init __stub(void) \ + { \ + return fn(); \ + } \ + __ADDRESSABLE(__stub) #else #define __initcall_section(__sec, __iid) \ #__sec ".init" + +#define __initcall_stub(fn, __iid, id) fn + +#define __define_initcall_stub(__stub, fn) \ + __ADDRESSABLE(fn) #endif #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS -#define ____define_initcall(fn, __name, __sec) \ - __ADDRESSABLE(fn) \ +#define ____define_initcall(fn, __stub, __name, __sec) \ + __define_initcall_stub(__stub, fn) \ asm(".section \"" __sec "\", \"a\" \n" \ __stringify(__name) ": \n" \ - ".long " #fn " - . \n" \ + ".long " __stringify(__stub) " - . \n" \ ".previous \n"); #else -#define ____define_initcall(fn, __name, __sec) \ +#define ____define_initcall(fn, __unused, __name, __sec) \ static initcall_t __name __used \ __attribute__((__section__(__sec))) = fn; #endif #define __unique_initcall(fn, id, __sec, __iid) \ ____define_initcall(fn, \ + __initcall_stub(fn, __iid, id), \ __initcall_name(initcall, __iid, id), \ __initcall_section(__sec, __iid))